With the general objective of investigating the etiology of IUGR and prematurity, this study proposes to test the hypotheses that: 1) family functioning, family structure, and changes in life events are important risk factors in IUGR and prematurity after adjusting for other known determinants (biomedical, anthropometric, socioeconomic, and behavioral); 2) a major biologic pathway through which these influences are mediated is the modification of cervical and systemic immune protection affecting the incidence of genitourinary tract infection during pregnancy; and, 3) family functioning, family structure, and changes in life events are important determinants of prenatal medical compliance. 2,200 subjects will be recruited who are patients at Family Medicine Clinics at two sites and who initiate prenatal care by the 32nd week of gestation. Information about medical history, demographics, family structure and functioning, and life events will be collected through structured interviews at the initial prenatal visit and at a 36-40 week visit. Assessments of immune status and infection will be made at these times, along with anthropometric measurements taken at each prenatal visit. Infant outcome will be assessed between 12-24 hours of birth using anthropometric measurements, Dubowitz assessment, skinfold measurements, and an evaluation of immune status and infection. other data collected postpartum from medical records will include prenatal chart summary, delivery data summary and postpartum discharge summary. Data will be analyzed using a three-tiered analysis including multivariate analysis.